Unix Timestamp Converter

Use it when your task matches one of these common needs: Convert a UTC date and time into Unix seconds for logs or APIs. Convert Unix seconds or milliseconds into an ISO UTC timestamp. It works best when you already know a UTC date and time, or a numeric Unix timestamp with the seconds or milliseconds unit selected.

In plain language: Date mode reads the entered date and clock time as UTC, uses Date.UTC to count milliseconds since 1970-01-01T00:00:00Z, then divides by 1,000 for Unix seconds. Timestamp mode reverses that by multiplying seconds by 1,000 or reading milliseconds directly before displaying the UTC ISO time. The examples on the page are there so you can compare your inputs with a UTC timestamp example before copying the answer.

Date to timestamp mode: Use this when you have a UTC calendar date and UTC clock time and need Unix seconds plus milliseconds. Timestamp to date mode: Use this when you have a stored epoch value and need to read the matching UTC date-time. UTC date: The calendar date is read as UTC, not as your computer or phone time zone. UTC time: The clock time is read as UTC. Convert local times to UTC first when the source time came from a local schedule. Timestamp: Enter the epoch number only. Unix seconds are usually 10 digits for modern dates, while JavaScript-style milliseconds are usually 13 digits. Unit: Choose seconds for compact Unix timestamps and milliseconds for JavaScript Date-style values.

Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.

The converter uses UTC on purpose. It does not guess your local time zone, daylight-saving rules, database storage format, or event-scheduling rules, so the same timestamp can appear as a different wall-clock time in another app. Check the mode, confirm the time is already in UTC, and make sure you did not paste a millisecond timestamp while seconds is selected.

Both show up in real tools. Unix timestamp usually means seconds since the Unix epoch, while JavaScript Date values use milliseconds. For example, 1777464000 seconds and 1777464000000 milliseconds point to the same UTC instant.

No. It treats the date and time fields as UTC and displays converted timestamps as UTC ISO time. A local app can display the same instant differently after applying its own time-zone rules.

The Unix epoch is 1970-01-01T00:00:00.000Z. A timestamp of 0 seconds means that exact UTC instant, and positive values count forward from there.

The usual causes are using local time as if it were UTC, choosing seconds when the value is milliseconds, or reading the result in an app that applies a local time zone or daylight-saving rule.

Not by itself. This converter shows one UTC instant. Scheduling real events needs the intended local time zone, daylight-saving behavior, recurrence rules, and the application rules that store or display the event.

No. The conversion runs in your browser tab with JavaScript date math, so the timestamp value does not need to be sent to a server.